Fig. 6.— Correlation between proteinases in bronchoalveolar lavage fluid (BALF) and factors associated with acute lung injury. Note that matrix metalloproteinase (MMP)-;2 expression is not correlated with the oxygen tension in arterial blood (Pa,O2)/inspiratory oxygen fraction (FI,O2) ratio (rs=−0.40, p=0.06) (a), lung wet-to-dry weight ratio (rs=0.40, p=0.06) (d), or number of neutrophils in BALF (rs=0.33, p=0.12) (g); whereas, MMP-;9 expression has a clear negative correlation with the Pa,O2/FI,O2 ratio (rs=−0.71, p=0.0001) (b) and is significantly correlated with the lung wet-to-dry weight ratio (rs=0.52, p=0.01) (e) and number of neutrophils in BALF (rs=0.73, p<0.0001) (h). As with MMP-;9, elastase activity in BALF correlates with Pa,O2/FI,O2 ratio (rs=−0.43, p<0.05) (c), with lung wet-to-dry weight ratio (rs=0.63, p<0.005) (f), and with number of neutrophils in BALF (rs=0.61, p<0.005) (i). AU: arbitrary unit.